title: Depinning dynamics of two-dimensional magnetized colloids on a random substrate.
abstract: We perform Langevin simulations on the depinning dynamics of two-dimensional magnetized colloids on a random substrate. On increasing the magnetic field strength, we find for the first time a crossover from plastic to smectic flows as well as a crossover from smectic to elastic crystal flows above depinning. For both the smectic and elastic crystal flows, a power-law scaling relationship could be obtained between the average velocity and applied driving force. The scaling exponent is found to be larger than 1 for smectic flow. But, for the elastic crystal flow, the scaling exponent is found to be less than 1. For the plastic flow, no power-law scaling relationship between the average velocity and applied driving force can be derived and history dependence of the depinning occurs. Within the crossover from plastic to smectic flows, a sudden decrease in the critical driving force is observed, and a sudden increase is found in the critical driving force across the crossover from smectic to elastic crystal flows, accompanied by a crossing of the curves of average velocity versus driving force.
authors.affiliation: School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, People's Republic of China. physycao@zzu.edu.cn
authors.forename: Y G
authors.initials: YG
authors.lastname: Cao
authors.forename: Q X
authors.initials: QX
authors.lastname: Li
authors.forename: G Y
authors.initials: GY
authors.lastname: Fu
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: H Z
authors.initials: HZ
authors.lastname: Guo
authors.forename: X
authors.initials: X
authors.lastname: Hu
authors.forename: X J
authors.initials: XJ
authors.lastname: Li
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003460:Crystallization; D004548:Elasticity; D008280:Magnetics; D015233:Models, Statistical; D010825:Physics / Q000379:methods; D010969:Plastics / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D003102:Colloids; D010969:Plastics